1. Field of the Invention
The present invention relates to apparatus and methods for the cleaning of test probes. In particular, the present invention relates to oxidizing debris on a test probe with an oxidizing agent and removing the oxidized debris with a cleaning agent.
2. State of the Art
In a typical semiconductor device manufacturing process, a plurality of integrated circuitry (IC) components are formed on a wafer, such as a silicon wafer. Once the IC components are formed, the wafer is diced into individual chips. These chips are then packaged for use, as known in the art.
The formation of the IC components requires numerous individual processing operations, primarily material layering and patterning, performed in a specific sequence. Each of these operations must be precisely controlled and monitored so that the IC components operate with the required electrical characteristics. However, even though the operations are precisely controlled and monitored, IC component failures still occur. Thus, it is important to detect the defective IC components as early as possible to prevent the unnecessary expense of continuing the fabrication of the defective IC components.
The IC components are generally tested after they are fabricated on the wafer and just prior to the dicing the wafer into individual chips. A typical method of testing the electrical characteristics of the IC components requires physical contact with the wafer surface. As shown in FIG. 7, the physical contact generally comprises contacting a plurality of bond pads 202 on an IC wafer 204 (defined as a wafer having IC components and material layers thereon) with a plurality of test probes 206 housed in a probe housing 208. The test probes 206 are usually fabricated from metal material and reside in vias 212 that extend into the probe housing 208. The test probes may be biased by a spring mechanism 214. The test probes 206 are each in electrical contact with traces 216 (shown as dashed lines) within the probe housing 208 which directs electrical test signals to the IC wafer 204. The test probes 206 extend out of the probe housing vias 212 to contact the IC wafer bond pads 202. The IC wafer bond pads 202 are in electrical contact with IC components (not shown) through a plurality of traces 218 (shown as dashed lines) within the IC wafer 204.
As shown in FIG. 8, each test probe 206 has a tapered tip 222 that presses into the IC wafer bond pad 202. Pressing the test probe tapered tip 222 into the IC wafer bond pad 202 helps ensure that the test probe 206 makes sufficient electrical contact with the IC wafer bond pad 202 for testing purposes. Thus, the IC component within the IC wafer 204 can be tested for specific electrical characteristics by sending and/or receiving signals through the test probe 206. The IC components that fail the test procedure are "mapped" such that when the IC wafer 204 is diced the chips containing the failing IC components can be culled.
The IC wafer bond pad 202 is general made from a conductive material, including copper, aluminum, solder (lead/tin alloy), or the like. One problem which occurs in such a testing procedure is the buildup of debris 224 on the test probe tapered tip 222, as shown in FIG. 9. The debris 224 primarily comprises the conductive material of the IC wafer bond pad 202 that is "picked" off the IC wafer bond pad 202 by the test probe tapered tip 222, and/or otherwise coats the test probe tapered tip 222. The debris 224 can prevent sufficient electrical connectivity between the test probe 206 and the IC wafer bond pad 202. If sufficient electrical connectivity is not achieved, the test procedure will result in a false fail indication, which may result in a potential culling of a "good" IC chip. Thus, the debris 224 must be removed from the test probe tapered tips 222.
One method of cleaning test probes 206 is to manually brush or otherwise abrade the test probe tapered tips 222. However, an abrasive method can spread the debris 224 and can wear the critical tapered tips 222 of the test probes 206.
A non-abrasive method of cleaning test probe tapered tips 222 is to spray a chemical solvent on the test probes 206 to dissolve the debris 224. However, such cleaning processes can force the debris 224 and moisture into the probe housing 208. The debris 224 and moisture can cause ionization, which can result in leakage and shorting failures, thus yielding erroneous test results. Furthermore, the debris 224 can become trapped in the probe housing vias 212 that can cause the test probe 206 to stick in the probe housing via 212 and not contact the IC wafer bond pad 202. Thus, the stuck test probe would generate a false fail indication.
Therefore, it would be advantageous to develop apparatus and techniques to clean test probes while eliminating the inherent problems with present techniques of test probe cleaning.